1. Field of the Invention
The present disclosure relates generally to machinery manufacturing, more specifically, to an improved spindle head structure rotatable in A/B axes.
2. Description of the Related Art
Commonly, a coordinate axis rotating around X-axis, Y-axis and Z-axis of a machine tool are described as A-axis, B-axis and C-axis respectively. Generally, a spindle head which may rotate around both the X-axis and Y-axis may be described as a spindle head rotatable in A/B axes or an A/B swing head, and a spindle head which may rotate around both the X-axis and the Z-axis may be described as a spindle head rotatable in A/C axes or an A/C swing head.
Conventionally, most machining centers are equipped with two-rotation-axis spindle heads, such as spindle heads rotatable in A/C axes.
However, the spindle head rotatable in A/B axes has a rotational range smaller than that of the spindle head rotatable in A/C axes whereas the manufacturing efficiency thereof is higher with decreased distortion during the manufacture. Particularly, the spindle head rotatable in A/B axes has advantages during manufacture of components which need lots of cutting, such as some complicated components in a thin-walled aircraft. Recently, the Spindle head rotatable in A/B axes becomes a key component in machining area. For instance, a Z3 spindle head commercially available from DS Technologie Company, Germany is developed on the parallel mechanism, and achieves great commercial success. The Z3 spindle head has three degrees of freedom including two rotational degrees of freedom along A and B axes and a translational degree of freedom along Z-axis.
However, when used in a machining center, it normally meets practical use when the spindle head may have rotational degrees of freedom in A and B axes. Therefore, to machine with high-speed and high-precision etc, it is necessary to develop a novel decoupled spindle head which is rotatable in A/B axes.
There are many shortcomings of the conventional dual-axis-rotatable spindle head, such as a complex structure, poor accuracy, a low stiffness, and high cost.